This invention relates to repairing a weld joint formed between two pipe sections and, in particular, to a tool for cleaning out the inside of the weld joint after a defective section of the joint has been removed.
In many pipe welding applications the integrity of pipe weld joint is inspected using a non-destructive inspection techniques, such as X-ray or the like, to determine if the weld is strong enough for its intended purpose. The inspection of pipe welds is vital in the construction of nuclear power plants and or high pressure vessels where a failure in the weld could lead to a serious and potentially dangerous equipment failure. Codes governing the fabrication of these units dictate that the welds be inspected after completion to determine if they are acceptable. In the event a crack or void is found in the joint, the defective area is usually removed and replaced with new weld material.
To repair an unacceptable weld, it is the common practice in the art to grind away the weld material in the defective segment of the weld joint while leaving the acceptable section of the weld in place. This creates a void in the joint in the form of a slotted opening that is later closed by adding new weld material. Prior to adding the new weld, the peripheral surfaces surrounding the void left by the removal of defective weld must be cleaned or prepared to accept the new weld. The base metal surrounding the void is typically hand filed to remove burrs and oxidized metal that can adversely affect the soundness of the new weld. Removal of unwanted materials from the exterior surfaces surrounding the repair opening can usually be accomplished without difficulty. Preparing the more difficult to reach interior surfaces, however, often times poses a greater problem. If these surfaces are not properly prepared there is a high probability that the repaired weld will again fail inspection, whereupon, the piece must be scrapped or further reworked. In any event, failure to properly repair the weld can be both costly and time consuming.
Heretofore, it has been the practice in the art to clean the inside of the repair joint area with a tool called a "hook file". As the name implies, the hook file typically is a circular file having a hook-like appendage at one end that can be passed through the repair opening into the interior of the pipe joint. The hook end of the file is brought under the lip of the repair opening and hand worked to abrade or scrap away unwanted material on the interior surface of the new weld joint. A hook file is usually made of high carbon steel which has been hardened and is therefore relatively expensive and the cost of repairing the weld becomes correspondingly high. Beyond this, the time to complete the hand filing operation on these difficult to reach surfaces is relatively long. Even after extensive working it is hard to judge if the operation has been successfully completed.